A045533 Concatenate the n-th and (n+1)st prime.
23, 35, 57, 711, 1113, 1317, 1719, 1923, 2329, 2931, 3137, 3741, 4143, 4347, 4753, 5359, 5961, 6167, 6771, 7173, 7379, 7983, 8389, 8997, 97101, 101103, 103107, 107109, 109113, 113127, 127131, 131137
Offset: 1
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Programs
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Haskell
a045533 n = a045533_list !! (n-1) a045533_list = f $ map show a000040_list :: [Integer] where f (t:ts@(t':_)) = read (t ++ t') : f ts -- Reinhard Zumkeller, Apr 20 2012
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Magma
[Seqint(Intseq(NthPrime(n+1)) cat Intseq(NthPrime(n))): n in [1..50 ] ]; // Marius A. Burtea, Mar 21 2019
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Mathematica
#[[1]]*10^IntegerLength[#[[2]]]+#[[2]]&/@Partition[Prime[Range[40]],2,1] (* Harvey P. Dale, Jun 06 2015 *)
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PARI
a(n) = eval(concat(Str(prime(n)), Str(prime(n+1)))); \\ Michel Marcus, May 11 2014
Formula
a(n) = prime(n)*(10^floor(log_10(prime(n+1)))+1) + prime(n+1). - Conner L. Delahanty, May 10 2014
Extensions
Offset changed to 1, in agreement with (almost?) all references to this sequence, by M. F. Hasler